Got my first electric bill for the summer (that included running the air 24/7) It was actually very reasonable. I was happy. My husband is a firm believer in staying cool, so we don't keep our thermostat set very high. We do however use fans to help keep us cooler so that is a saving factor. We also grill alot during the summer to keep from heating up the house. Also I dont bake as much during the summer months. Using a crock pot is also another way to keep down costs.
A few more ideas for keeping cool, wear a wet kerchief around your neck, when we went to RiverFest on Memorial Day weekend, we took our big kerchiefs and wet them and wore them around our necks, it helped immensely. Also if your power goes out and it gets hot, try sleeping on the floor, it is cooler there. Just pull your mattress off your bed and sleep on it on the floor.
Also with summer time you have bright sunshine, so letting it in for light, will make you have to use your lights less, just make sure your not letting in heat with that light, that will defeat your purpose.
Hope your all having a wonderful summer and staying cool!!